U.S. patent number 5,133,321 [Application Number 07/698,671] was granted by the patent office on 1992-07-28 for integrated throttle control and idle validation sensor.
Invention is credited to Charles A. Hering, David A. Schaller.
United States Patent |
5,133,321 |
Hering , et al. |
July 28, 1992 |
Integrated throttle control and idle validation sensor
Abstract
An integrated throttle control and idle validation sensor
includes mechanically coupled but electrically independent throttle
control and idle validation components. A single mechanical input
to the protective sensor housing corresponds to an accelerator
pedal position and causes selective coupling of a supply voltage to
one of an idle validation conductor and a throttle validation
conductor for interpretation by an electronic control system. The
throttle control system within the sensor housing comprises a
potentiometer adapted for movement corresponding to the mechanical
input whereby a variable voltage throttle control signal may be
delivered to the electronic fuel control system. The sensor
integrates previous separate throttle control and idle validation
functions into a single environmentally secure housing and requires
no calibration. The disclosed throttle system is more reliable and
less costly than previously available separate throttle control and
idle validation functions.
Inventors: |
Hering; Charles A. (Portland,
OR), Schaller; David A. (Fort Wayne, IN) |
Family
ID: |
24806219 |
Appl.
No.: |
07/698,671 |
Filed: |
May 10, 1991 |
Current U.S.
Class: |
123/399; 338/153;
338/162 |
Current CPC
Class: |
F02D
9/02 (20130101); F02D 41/28 (20130101); F02D
11/106 (20130101); F02D 2009/0294 (20130101); F02D
2400/08 (20130101); F02D 2200/602 (20130101); F02D
2250/16 (20130101) |
Current International
Class: |
F02D
11/10 (20060101); F02D 41/24 (20060101); F02D
9/02 (20060101); F02D 41/00 (20060101); F02D
007/00 () |
Field of
Search: |
;123/399,361,339 ;74/513
;180/197,335 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Nelli; Raymond A.
Attorney, Agent or Firm: Harrington; Robert L.
Claims
We claim:
1. A throttle control and validation sensor for sensing an
accelerator control device position and providing a control device
position signal and a position validation signal each representing
control device position, the sensor comprising:
a sensor housing;
mechanical input means corresponding to accelerator control device
position for delivering interior of said housing a mechanical
indication of accelerator control device position;
integrated sensor and validation means within said housing,
mechanically coupled in common to said mechanical indication of
accelerator control device position, and responsive thereto for
generating said position signal and said validation signal; and
signal delivery means making available said position signal and
said validation signal exterior of said housing.
2. A sensor according to claim 1 wherein said position signal is a
continuous signal identifying an accelerator control device
position relative to a full control device position range.
3. A sensor according to claim 1 wherein said validation signal is
a discrete signal identifying accelerator control device position
within a given range of control device positions, said given range
being less than a full range of control device positions.
4. A sensor according to claim 3 wherein said given range of
control device positions corresponds to an idle condition of said
control device.
5. A sensor according to claim 1 wherein said validation signal
identifies accelerator control device position within a plurality
of control device position ranges, each of said plurality of ranges
being less than a full control device position range and mutually
exclusive thereamong.
6. A sensor according to claim 5 wherein a first range of said
plurality of ranges corresponds to an idle condition of said
control device and a second one of said ranges corresponds to
non-idle throttle condition of said control device.
7. A sensor according to claim 1 wherein said housing is adapted to
protect said integrated sensor and validation means against
environmental conditions surrounding said housing.
8. An integrated throttle control sensor and idle validation sensor
for an apparatus having an accelerator control device and
electronic fuel control system, the accelerator control device
being manually positionable to indicate throttle control by way of
said sensor to said electronic fuel control system, said sensor
comprising:
housing means adapted for mounting to the accelerator control
device and sealable to substantially isolate the interior of said
housing against environmental conditions surrounding said
sensor;
mechanical input means to said sensor wherein said mechanical input
to said sensor corresponds to manual throttle control positioning
of said control device;
sensor means within said housing and responsive to said mechanical
input to generate an electrical throttle control signal
corresponding to control device position and a bi-state electrical
idle validation signal having a first state corresponding to an
idle condition of said control device and a second state
corresponding to a non-idle condition of said control device;
and
electrical output means making available said throttle control
signal and said idle validation signal external of said housing for
coupling to said electronic fuel control system.
9. A sensor according to claim 8 wherein said sensor means further
produces a bi-state throttle validation signal having a first state
corresponding to a throttle condition of said control device and a
second state corresponding to a non-throttle condition of said
control device, and wherein said electrical output means makes
available external of said housing said throttle validation
signal.
10. A sensor according to claim 8 wherein said mechanical input
comprises a member rotatably mounted within said housing and having
a range of rotation corresponding to a range of control device
positions.
11. A sensor according to claim 8 wherein said sensor means
comprises:
a potentiometer having a first wiper and a resistive element, the
first wiper in contact with said resistive element, the resistive
element carrying a first electrical potential thereacross whereby
in response to said mechanical input said first wiper moves
relative to said resistive element such that the electric potential
at said first wiper corresponds to said throttle control signal;
and
a switch having a second wiper and a contact element, the second
wiper carrying a second electrical potential and the contact
element carrying said idle validation signal whereby in response to
said mechanical input said second wiper moves in coordination with
said first wiper and relative to said contact element such that
said second wiper selectively couples said second electrical
potential to said contact element according to control device
position.
12. A sensor according to claim 11 wherein said mechanical input
means comprises a body rotatable within said housing and carrying
said first and second wipers for mechanical coupling and
coordinated movement thereof.
13. A sensor according to claim 11 wherein said second wiper is
adapted to selectively contact a second conductive element
according to control device position whereby a throttle validation
signal may be taken from said second conductive element, and
wherein said electrical output means makes available said throttle
validation signal exterior of said housing.
14. An integrated throttle control signal and idle validation
sensor comprising:
sensor housing means adapted for mounting to an accelerator control
device and sealable to substantially isolate the interior of said
housing against environmental conditions surrounding said
sensor;
mechanical input to the interior of said housing and adapted for
movement corresponding to accelerator control device movement;
first conductive element interior of said housing;
second conductive element interior of said housing;
first wiper interior of said housing and adapted for selective
electrical contact with said first and second conductive
elements;
a resistive element interior of said housing;
second wiper element interior of said housing and adapted for
electrical contact along the length of said resistive element;
and
mechanical coupling means interior of said housing and responsive
to said mechanical input for relative coordinated movement of said
first and second wipers relative to said first and second
conductive elements and said resistive element, respectively,
whereby movement of the accelerator control device from an idle
position through a full throttle position corresponds to said first
wiper contact with said first conductive element and subsequent
contact with said second conductive element and continuous contact
of said second wiper element with said resistive element.
Description
BACKGROUND OF THE INVENTION
The present invention applies to engine control systems and
particularly to throttle control systems for electronic fuel
control systems.
Many vehicle throttle control systems now use electrical circuitry
to deliver an electrical signal from the accelerator, e.g. an
accelerator pedal or hand control lever, to an electronic fuel
control system. For example, a voltage signal provided to the
electronic fuel control system corresponds to accelerator pedal or
hand control position. When an "in-range" voltage level arrives at
the electronic fuel control system, the electronic fuel control
system responds by injecting a corresponding volume of fuel into
the engine fuel system.
In some applications, a control device failure can result in an
invalid in-range throttle condition, i.e. an unintended in-range
voltage level. Under such condition, even though the accelerator
control device is at an idle position, the electronic fuel control
system receives an erroneous throttle control signal and
undesirably injects fuel into the engine fuel system. Loss of
engine throttle control, and possibly unintended vehicle
acceleration, can result. To avoid such error conditions, a
separate idle validation switch has been added to the accelerator
control device as backup protection against such a failure.
Typically, this switch provides a single pole double throw function
wherein one side of the switch delivers a logic signal
corresponding to valid idle operation only and the other side
validates throttle operation. The switch mounts to the accelerator
control device in such a way that actuation of the accelerator
control changes the switch position from its idle validation
position to its throttle validation position. The electronic fuel
control system ignores the throttle control signal until it
receives a throttle validation signal by way of the switch.
Accordingly, if an erroneous in-range throttle signal arrives at
the electronic fuel control system, unintended fuel delivery is
avoided because the electronic fuel control system has not yet
received a throttle validation signal.
The idle validation switch attaches to the accelerator pedal or
hand control as a separate component. The switch mounts to the
accelerator control device in such manner to provide the switching
according to pedal or hand control lever position. It is necessary
to adjust or calibrate the point at which the switching occurs to
coincide with a specified throttle signal level, i.e. a point of
transition between idle and throttle operation. This insures that
the switch is in the idle valid mode when the driver releases the
accelerator control device, and that the engine will have a smooth
idle to power transition when the driver applies the throttle.
Switch transition points are typically specified by the engine
manufacturer. Installation of the switch can be difficult because
of the sensitive calibration required to meet the engine
manufacturer's specifications, and the complex test procedures
needed to insure that proper switch functioning occurs.
Additionally, the switch must meet stringent environmental quality
standards to function reliably in typical operating
environments.
These factors result in an expensive idle validation switch and, in
some cases, marginal product reliability. The resulting product is
also virtually impossible to service in the field without replacing
the entire accelerator control assembly. Such difficult field
service further adds to the overall cost of such idle validation
systems.
SUMMARY OF THE INVENTION
In accordance with a preferred embodiment of the present invention,
an accelerator position sensor is combined in an integrated sensor
package with mechanical registration of the validation switch and
throttle control sensor built into the sensor. The accelerator
position sensor and idle validation switch are electrically
separate units, but mechanically coupled for response to a common
actuation mechanism. The common mechanical connection establishes
and maintains constant the required mechanical registration. The
resulting integrated sensor can be installed on the control device
without significant adjustment, or without calibration of the
switch and sensor. Also, packaging of the idle validation switch in
the sensor housing protects the switch from its environment, and
thereby increases its reliability. The integrated package thereby
enjoys reduced number of parts, increased reliability and
serviceability, and reduced overall cost.
BRIEF DESCRIPTION OF THE DRAWINGS
For a better understanding of the invention, and to show how the
same may be carried into effect, reference will now be made, by way
of example, to the accompanying drawings in which like reference
numerals refer to like elements.
FIG. 1 is a side view of an accelerator pedal, an integrated
throttle control and idle validation sensor, and an electronic fuel
control system.
FIG. 2 is a sectional view of the pedal and sensor of FIG. 1 taken
along lines 2--2 of FIG. 1.
FIG. 3 is a perspective view of the integrated throttle control and
idle validation sensor of FIG. 1.
FIG. 4 is an exploded view of the sensor of FIG. 3.
FIG. 5 is a schematic diagram of the sensor and electronic fuel
control system showing electronic coupling.
FIG. 6 illustrates the relationship between mechanical operation of
the sensor and production of the throttle control signal, idle
validation signal and throttle validation signal.
DETAILED DESCRIPTION
FIG. 1 shows a fuel control device, i.e., an accelerator pedal 10,
pivotally coupled at pin 12 to a base plate 14. Base plate 14
attaches to the floor of a vehicle (not shown) in conventional
manner. An integrated throttle control and idle validation sensor
16 mounts to the underside of pedal 10 for the combined functions
of providing a throttle control signal, an idle validation signal,
and a throttle validation signal. Sensor 16 couples by way of
multi-conductor cable 18 to an electronic fuel control system 20.
System 20 is a conventional control system, and in the illustrated
embodiment corresponds to a Cummins electronic fuel control system
available under the trade name CELECT. While illustrated with
reference to a specific electronic fuel control system, it will be
appreciated by those skilled in the art that sensor 16 may be
adapted to operate with a wide variety of electronic fuel control
systems and control devices.
A lever arm 22 pivotally mounts to sensor 16 and carries a roller
24 at its distal end. Base plate 14 includes an inclined surface 26
engaged by roller 24. As the operator depresses pedal 10 to
accelerate the vehicle, pedal 10 rotates about pin 12 in the
direction 30, clockwise in the view of FIG. 1. As roller 24 moves
upward along surface 26 in response to downward actuation of pedal
10, lever arm 22 pivots in the direction 32, counter clockwise in
the view of FIG. 1, about the axis 34. Sensor 16 detects such
movement of lever arm 22 and delivers to system 20 by way of cable
18 suitable signals both indicating and validating the position of
pedal 10.
FIG. 2 shows a sectional view of the assembly of FIG. 1 taken
through the sensor 16 and arm 22. In FIG. 2, a double spring 40
encircles a shaft 42 mounted upon the body of pedal 10 for rotation
about the axis 34. Spring 40 couples the underside of pedal 10 and
lever arm 22 to bias lever arm 22 in the direction 33 opposite that
of direction 32. Pedal 10 is thereby spring biased in the direction
31, opposite of direction 30, and toward the idle position as shown
in FIG. 1. The shaft 42, pivotally mounts to the body of pedal 10,
but fixedly attaches to lever arm 22 such that movement of pedal 10
results in rotation of shaft 42 relative to sensor 16 and about the
axis 34. Sensor 16, being mechanically coupled to shaft 42,
responds to rotation of shaft 42 by producing the desired throttle
control, idle validation, and throttle validation signals according
to pedal 10 position as described hereinafter.
FIG. 3 shows in perspective the throttle control and idle
validation sensor 16. Sensor 16 includes a slot formation 46 for
mechanical coupling to shaft 42 and an electrical connector
formation 48 for electrical coupling to multi-conductor cable 18.
Shaft 42 engages slot formation 46 and rotates slot formation 46
about the axis 34 as a mechanical input to sensor 16. Movement of
pedal 10 about pin 12 results in mechanical input, by way of shaft
42, to sensor 16 at slot formation 46. In response, sensor 16
generates the necessary signals at the connector formation 48 for
delivery by way of cable 18 to electronic fuel control system 20.
It will, therefore, be appreciated by those skilled in the art that
sensor 16 provides an integrated package receiving a mechanical
input and developing suitable electrical outputs. Sensor 16
requires no calibration for idle validation relative to throttle
control as such is built into the integrated package. Also, by
enclosing the throttle control and idle validation functions in the
housing of sensor 16, the risk of exposure to environmental
conditions, possibly effecting operation of sensor 16, is
eliminated.
FIG. 4 is a view of sensor 16 exploded along the axis 34. In FIG.
4, sensor 16 comprises an external housing 50, a seal 52, a printed
circuit element 54, a termination wedge 56, a rotor 58, a spring
60, and a cover 62. Within housing 50, a terminal structure 64
carries conductive elements, corresponding to those of cable 18,
from within the connector formation 48 to the interior of housing
50. As described more fully below, the printed circuit element 54
includes a resistive element 66, an idle conductive element 68, and
a throttle conductive element 70 suitably etched onto the substrate
of circuit element 54. The rotor 58 includes a throttle wiper 72
and an idle/throttle validation wiper 74. In assembly of sensor 16,
seal 52 first inserts within housing 50, then circuit element 54
rests within housing 50 such that elements 66, 68, and 70 of
circuit element 54 face inward. A flat portion 76 of printed
circuit element 54 rests adjacent the terminal structure 64.
Circuit element 54 includes additional conductive traces (not
shown) for coupling elements 66, 68, and 70 to suitable terminal
contact points (not shown) of flat portion 76. The termination
wedge 56 suitably interconnects the elements 66, 68, and 70 of
element 54, by way of the terminal contacts (not shown) of flat
portion 76, with the conductors of terminal structure 64.
Electrical coupling between individual conductors of cable 18 and
portions of circuit element 54 is thereby established.
Rotor 58 inserts within housing 50 interior of circuit element 54
and the wipers 72 and 74 contact portions of circuit element 54.
More particularly, the throttle wiper 72 contacts the resistive
element 66 of circuit element 64 and the idle/throttle validation
wiper 74 selectively contacts one of, or neither of, the idle
conductive element 68 and the throttle conductive element 70. Seal
52 seal rotor 58 within housing 50 while allowing rotation about
the axis 14. Spring 60 couples rotor 58 and housing 50 to suitable
bias rotor 58 toward a full return position. Cover 62 attaches to
housing 50 to rotatably support rotor 54 and to seal the entire
assembly. Rotor 58 includes the slot formation 46 (not shown but
indicated by numeral 46 in FIG. 4). Rotor 58 then rotates within
housing 50 and about the axis 34 according to rotation of shaft 42,
i.e. in response to actuation of pedal 10. Throttle wiper 72
thereby moves along resistive element 66 while, for given ranges of
angular position for rotor 58, validation wiper 74 contacts one of
the idle validation conductive element 68, a non-conductive portion
69, or idle validation conductive element 70.
FIG. 5 illustrates electrical connections between portions of the
sensor 16 and the electronic fuel control system 20 as established
by the conductors of cable 18. In FIG. 5, the validation wiper 74
together with conductive elements 68 and 70 and non-conductive
portion 69 comprise a switch 78. The resistive element 66 and
throttle wiper 72 comprise a potentiometer 80. Switch 78 and
potentiometer 80 are mechanically coupled by way of rotor 58, but
are electrically separate. A voltage supply conductor 82 of cable
18 connects, by way of structure 64, wedge 56, and conductive
traces of circuit element 54, to wiper 74, i.e. to the common pole
of switch 78. An idle active conductor 83 of cable 18 couples in
similar manner to idle conductive element 68. A throttle active
conductor 84 of cable 18 similarly couples to throttle conductive
element 70. Switch 74 selectively routes the supply voltage present
on conductor 82 to neither or one of cable conductors 83 and 84 for
interpretation by electronic fuel control system 20. A supply
voltage potential on idle active conductor 83 validates an idle
position for pedal 10 while a supply voltage potential on throttle
active conductor 84 validates an in-range throttle control signal.
A supply voltage on neither of conductors 83 and 84, i.e., an open
connection, indicates to system 20 a transition between an idle
active and throttle active condition to pedal 10.
A second voltage supply conductor 85 of cable 18 delivers a supply
voltage to end 66b of resistive element 66 while a ground conductor
87 of cable 18 connects to the opposite end 66a of resistive
element 66 as a ground return to electronic fuel control system 20.
A throttle position conductor 86 of cable 18 couples to wiper 72 of
potentiometer 80 whereby the voltage potential on throttle position
conductor 86 corresponds to the position of wiper 72, more
particularly, to the position of pedal 10.
As noted above, the switch 78 and potentiometer 80 are mechanically
coupled by way of rotor 58. As rotor 58 moves from its full return
position through a given range of angular movement, corresponding
to full actuation of pedal 10, wiper 72 moves from near end 66b
toward end 66a of resistive element 66. Concurrently with such
rotation of rotor 54, wiper 74 initially contacts conductive
element 68, but as rotor 54 moves through a given angular
transition zone range, it disengages conductive element 68 as it
rests against non-conductive portion 69. At the end of this
transition zone range, wiper 74 contacts conductive element 70.
Thus, rotation of rotor 54 through its angular range of motion
corresponds to a continuously variable voltage signal on throttle
position conductor 86, and suitable presentation of discrete logic
signals on idle active conductor 83 and throttle active conductor
84.
In the preferred embodiment, rotor 54 has a full range of
approximately 70 degrees of rotation corresponding to movement of
pedal 10 from idle to full acceleration. The transition zone range,
between idle validation and throttle validation, is determined by
the extent of non-conductive portion 69 of circuit element 54
separating conductive elements 68 and 70. As will be apparent to
those skilled in the art, a variety of configurations for sensor 16
will yield a variety of rotor 54 movement ranges and transition
zone ranges a desired.
FIG. 6 relates the wiper 72 position in terms of a rotation angle
of rotor 58 on the horizontal axis to the throttle control signal
voltage, on the vertical axis, delivered to electronic fuel control
system 20 by way of conductor 86. As the angular position of rotor
58 moves from an idle position 100 to a full throttle position 102,
the voltage at wiper 72 ramps linearly from an idle voltage 104 to
a full throttle voltage 106. The wiper 74 similarly moves from
contact with idle conductive element 68 through a transition zone
108 and on to contact with throttle conductive element 70. Thus, as
rotor 58 moves from its idle position 100 to its full throttle
position 102, the voltage on conductor 83 of cable 18, representing
an idle active signal, remains at the supply voltage V.sub.s1 until
wiper 74 loses contact with conductive element 68. At this time the
idle active conductor 83 of cable 18 presents an open circuit to
system 20. Continuing with rotation of rotor 58 toward the full
throttle position 102, wiper 74 eventually contacts conductive
element 70 whereat the voltage on conductor 84 of cable 18,
representing a throttle active signal, moves from being open to the
supply voltage potential V.sub.s2.
Electronic fuel control system 20 monitors the throttle position
conductor 86, idle active conductor 83 and throttle active
conductor 84 of cable 18. A supply voltage potential on idle active
conductor 83 validates the idle position for pedal 10 and system 20
ignores the signal on throttle position conductor 86. A supply
voltage potential on throttle active conductor 84 validates an
in-range throttle control signal on throttle position conductor 86
and an appropriate volume of fuel is delivered to the vehicle
engine. An open circuit on both of conductors 83 and 84 indicates
to system 20 a throttle transition between an idle condition and a
throttle condition. System 20 reacts as programmed according to the
necessary engine specification requirements for transition between
idle and throttle.
Thus, an integrated throttle control and idle validation sensor has
been shown and described. The integrated package reacts to
accelerator pedal position by way of a single mechanical input and
delivers suitable electrical signals by way of cable 18 to an
electronic fuel control system. The sensor and validation switch
enjoy protection from environmental conditions, i.e. the cab
environment, by virtue of its integrated packaging. Also,
installation of sensor 16 requires no calibration between the
throttle control portions, i.e. wiper 72 and resistive element 66,
and the idle validation portions, i.e. the wiper 74 and conductive
elements 68 and 70.
It will be appreciated that the present invention is not restricted
to the particular embodiment or application that has been described
and illustrated and that many variations may be made therein
without departing from the scope of the invention as found in the
appended claims and the equivalents thereof. For example, while the
invention has been shown for a foot operated accelerator pedal, it
should be apparent that the invention may be applied to a variety
of control devices where separate validation signals are
desired.
* * * * *